事先我不得不说，我真的很抱歉格式不佳！我似乎无法掌握它...... 我也是一个R菜鸟。
所以， 我有80个文件，其中包含80条鱼类个体运动的信息;
> head(PAVdata)
X meanlat meanlong meandepth mindepth maxdepth depthrange rec numhits datetime mon X.1 Y Z
1 23 58.39601 8.708952 6.493529 5.72 7.47 1.75 4 17 2012-05-11 11:15:00 1 482986.7 6472838 6.493529
2 24 58.39618 8.710993 4.035588 1.76 7.47 5.71 6 34 2012-05-11 11:45:00 1 483106.1 6472855 4.035588
3 25 58.39615 8.710919 6.037692 3.08 8.35 5.27 6 26 2012-05-11 12:15:00 1 483101.8 6472853 6.037692
4 26 58.39556 8.710654 3.987500 2.20 6.16 3.96 5 16 2012-05-11 12:45:00 1 483086.0 6472787 3.987500
5 27 58.39617 8.711363 2.944615 2.20 3.96 1.76 6 26 2012-05-11 13:15:00 1 483127.8 6472855 2.944615
6 28 58.39628 8.710904 2.860000 2.20 3.52 1.32 6 24 2012-05-11 13:45:00 1 483101.0 6472867 2.860000
但感兴趣的列是日期时间和 Z ，其中Z是深度。
我的目标是做什么;
到目前为止我尝试过的是
六月＆LT; -C（PAVdata $日期时间[grep的（ “^ 2012-07”，as.character（PAVdata $日期时间））]）
这会产生一些对我来说完全牵强的东西
头（6月） [1] 2390 2391 2392 2393 2394 2395
我正在阅读子集和汇总和 POSIXlt 和 tapply 和动物园并想尝试这些，但我似乎得到了一个长度差异的错误..
继续尝试使用POSIXlt;
PAVdata $ datetime＆lt; - strftime（as.POSIXlt（PAVdata $ datetime，format =“％Y-％m-％d％H：％M：％S”），format ='％b'）
june_Monthly_Avg＆lt; - ave（PAVdata $ Z，PAVdata $ datetime，FUN = mean）
头（june_Monthly_Avg） [1] 9.341862 9.341862 9.341862 9.341862 9.341862 9.341862
整个事情由相同的数字组成...... 我认为我使用突击队非常错误。
但后来我尝试了更简单的事情;
juni_Monthly_Avg＆lt; - ave（PAVdata $ Z，PAVdata $ datetime，FUN = mean）
头（juni_Monthly_Avg）
[1] 6.493529 4.035588 6.037692 3.987500 2.944615 2.860000
对我来说很困惑，看到6月我只能得到一个值。 到目前为止，我认为 grep 看起来最有希望，但我似乎无法理解它。 一直拖着The R Book和interwebs，当然现在已经好几天了，决定在我拔掉头发之前（在咨询我的主管之前）大声呼救。
谢谢^ _ ^
> dput(head(PAVdata))
structure(list(X = 23:28, meanlat = c(58.3960117647059, 58.3961761764706,
58.3961507692308, 58.395558125, 58.3961726923077, 58.3962804166667
), meanlong = c(8.70895176470588, 8.71099294117647, 8.71091923076923,
8.71065375, 8.71136346153846, 8.71090416666667), meandepth = c(6.49352941176471,
4.03558823529412, 6.03769230769231, 3.9875, 2.94461538461538,
2.86), mindepth = c(5.72, 1.76, 3.08, 2.2, 2.2, 2.2), maxdepth = c(7.47,
7.47, 8.35, 6.16, 3.96, 3.52), depthrange = c(1.75, 5.71, 5.27,
3.96, 1.76, 1.32), rec = c(4L, 6L, 6L, 5L, 6L, 6L), numhits = c(17L,
34L, 26L, 16L, 26L, 24L), datetime = structure(1:6, .Label = c("2012-06-01 00:15:00", "2012-06-01 00:45:00",
"2012-06-01 01:15:00", "2012-06-01 01:45:00", "2012-06-01 02:15:00",
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"2012-07-10 23:45:00"), class = "factor"), mon = c(1L, 1L, 1L,
1L, 1L, 1L), X.1 = c(482986.747312444, 483106.142664631, 483101.821796104,
483086.019405256, 483127.799620954, 483101.003261731), Y = c(6472837.55691427,
6472855.34802117, 6472852.53770682, 6472786.61976395, 6472854.86710904,
6472866.97636095), Z = c(6.49352941176471, 4.03558823529412,
6.03769230769231, 3.9875, 2.94461538461538, 2.86)), .Names = c("X",
"meanlat", "meanlong", "meandepth", "mindepth", "maxdepth", "depthrange",
"rec", "numhits", "datetime", "mon", "X.1", "Y", "Z"), row.names = c(NA,
6L), class = "data.frame")
>
答案 0 :(得分：3)
你看起来你托盘很多东西，但你不会以一种好的方式尝试一件事。
例如，使用POSIXlt，这里的dat是您的PAVdata对象
ll <- as.POSIXlt(dat$datetime)
dat$hours <- ll$hour ## I create a variable hour
dat$days <- ll$mday ## I create a variable day
dat$months <- ll$mon ## I create a variable month
现在我可以使用此变量按组进行平均。
这是使用plyr包的解决方案。
ddply(dat,.(months,days),summarise, m = mean(meandepth)) ## I group by months and days
months days m
1 4 11 4.393154
> ddply(dat,.(months,days,hours),summarise, m = mean(meandepth))
months days hours m
1 4 11 11 5.264558
2 4 11 12 5.012596
3 4 11 13 2.902308
无论你使用什么，尝试以一种好的方式使用一件事。通常在R中有很多方法可以做这些事情。